Lampinsaari - ZINC Database

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Name	Lampinsaari	DATA UPDATED	2.11.2001
Secondary names	Vihanti mine, Isoaho
Site photo 1		Site photo 2
LOCATION
Geological domain	Svecofennian	Province	Vihanti Region
Regional map 1		Regional map 2
Map sheet	243405
Northing	7145820	Easting	2555350
Latitude	64.40660N	Longitude	25.14418E
Municipality	Vihanti
Nearest town, access	11 km SE from Vihanti, 70 km SSW from Oulu. Sealed road and railway to the mine.
MINING
Mine photo 1		Mine photo 2
Mine photo 3		Mine photo 4
Exploration licence no	633/1–12, 739/1, 1107, 2165/1	Mining concession no	633/1–12a, 2165/1a
Present holder	Outokumpu Oyj (1951–)
Previous holders	Geological Survey of Finland (GTK) (1946–50)
Status of development	Underground mine, closed
When mined	1954–92 [2,17].
Resources and grades
Total production	28 Mt ore: 1.4 Mt Zn, 129000 t Cu, 99500 t Pb,190 t Ag, 3038 kg Au [2,17].
Total in-situ content
Size of the deposit (Mt)		Size reference
Best sections
Extent of the deposit	1.5 km long, <50–200 m wide zone, extending to the depth of 1000 m [1,2,17].
Ore bodies	Several, 1–50 m thick, 50–200 m wide and 150–900 m long lodes: pyrite, zinc, chalcopyrite and Pb-Ag-Au lodes; the Zn and pyrite lodes are, nearly throughout the deposit, located 10–20 m apart [1,28].
Plan figure 1		Plan figure 2
Plan figure 3		Plan figure 4
Section figure 1		Section figure 2
Section figure 3		Section figure 4
EXPLORATION
Explor. site photo 1		Explor. site photo 2
Discovery year	1946
Discovery	By the GTK; the first indications were mineralised samples from glacial erractics found by amateur prospectors in 1936 and 1939; these led the GTK to discover the ore by drilling into an area indicated by glacial erratic boulder survey and as an electric and magnetic anomaly [1,2,6,7,28,33].
Exploration history	GTK (1936–50) [1,6,7,8,10,11,27,32,33]: Glacial erratic boulder survey, bedrock mapping, till geochemical survey, ground electric, gravimetric and magnetic survey, diamond drilling, mineralogical studies, lithogeochemical survey. Outokumpu (1951–) [1,9,12,14,16,23,27,28,29,30]: Diamond and percussion drilling, ground magnetic, gravimetric and electric surveys, pilot plant tests, mineralogical studies, bedrock mapping. GTK (1970's–1990's) [18,19,26]: Regional till- and stream-sediment geochemical investigations, a regional geomathemathical study.
Drilling	GTK (1946–50): 40 diamond-drill holes, total 5979 m [1,6,7]. Outokumpu (1951–): extensive diamond drilling in 25 m profiles across the ore; by the end of 1966 total drilling was 120 km [1].
Trench figure 1		Trench figure 2
Elements analysed	SiO2,TiO2, Al2O3, Fe2O3,MnO, MgO, CaO, Na2O,K2O, P2O5,LOI, Ag, As, Au, B, Ba, Be, Br, Co, Cr, Cu, Ga, La, Mo, Nb, Ni, Pb, Sb, Sc, Se, Sn, Sr, U, V, Zn by XRF+ICP+INAA [25].
Economic evaluations	The first resource estimates by the GTK in 1950 [6]. Full feasibility study by Outokumpu in 1952–54 [1].
Geophysical response	The pyrite lodes have a good response on slingram and gravimetry [7]. The black shales have a strong response on both magnetic and electric methods [2].
Geophys. anomaly fig. 1		Geophys. anomaly fig. 2
Petrophysics	Click here
Primary geochemical dispersion	An extensive Zn anomaly in dolomites and skarns and a similar Pb anomaly in all local rocks, except the black shales [25]. The sequence of increasing lateral extent of the anomalies is: Cu, Mo, U, Ba, Tl, As, Hg, Zn, Ag, Pb, Bi, Sb [28].
Secondary geochemical dispersion	Only a low-contrast, incoherent, areally restricted Zn-Pb-Cu anomaly in till; rather, the Zn anomalies in till reflect the locations of granitic rocks in the region [15,19]. Possibly, an Au anomaly in till related to the ore [18].
Primary anomaly fig. 1		Secondary anomaly fig. 1
Primary anomaly fig. 2		Secondary anomaly fig. 2
Primary anomaly fig. 3		Secondary anomaly fig. 3
Exploration geologist(s) in charge	GTK: Aimo Mikkola Outokumpu: Pentti Rouhunkoski
ORE
Ore outcrop photo 1		Ore outcrop photo 2
Major ore minerals	Sphalerite, pyrrhotite, galena, chalcopyrite, pyrite [1,12].
Minor ore minerals	Cubanite, vallerite, arsenopyrite, stannite, molybdenite, gold, silver, electrum, hessite, uraninite, magnetite, tetrahedrite, tennantite, gudmundite, boulangerite, bournonite, pyrargyrite, niccolite, gahnite, ullmannite, breithauptite, nisbite, bismuth, antimony [1,12,16,23,33].
Ore mineral photo 1		Ore mineral photo 2
Ore mineral photo 3		Ore mineral photo 4
Gangue	Diopside, tremolite, baryte, quartz, dolomite, rutile, graphite, tourmaline, fluorite [1].
Zoning	The Lampinsaari lode: Zn shows the highest grades in the central and lower, Cu in the central and Pb in the lower parts of the lode [1]. Ag follows Pb throughout the deposit; there are separate, disseminated, Pb-Ag-Au mineralisations in the area between the Zn lodes and black shale [1,28]. Pyrrhotite-rich margins in the pyrite lodes [1]. A separate U-P rich horizon [4,17].
Ore composition	Click here	Ore mineral compositions	Click here
Primary structures	Bedding in greywacke and dolomite, and, locally, clastic texture in the greywacke; banding the Zn lodes? [1,11].
Ore fabric	Massive banded and non-banded, and disseminated sulphide ore with common sulphide±sulphosalt veins [1,11,27]. Grain size of ore minerals is 0.05–1 mm [1]. Pyrite is commonly euhedral and forms porphyroblasts up to 10 cm in diameter (esp. in the pyrite lodes) [1].
Enriched components	Ore, enriched: Ag, As, Au, Ba, Bi, Mg, Pb, S, Sb, Se, Zn, depleted: Ca, P, immobile(?): Co, Ni [1,3]. Cordierite gneiss, enriched: B, Cu, Fe, Mg, S, Zn, depleted: Ca, K, Na, Si (interpreted from [1]).
Geothermo- and barometry	Sphalerite: 5.8–8.0 kbar (mean: 6.8 kbar) [21]. Remobilisation, according to sphalerite, at 570°C [1].
Ore fluid
Stable isotope data	δ13C in black shale: -16.08 per mill reflecting an effect of alteration into the originally biogenic C-isotope ratio [2]. δ34S, in footwall graywacke: +0.5 – +0.9 per mill (pyrite), in disseminated Cu lode: +2.2 – +4.8 per mill (pyrite),+3.2 – +5.7 per mill (pyrrhotite) [4]. Average values of δ34S: in black shale -5.6 per mill (pyrrhotite), in Zn ore +7.5 per mill (sphalerite, pyrite, pyrrhotite); cordierite gneiss: +8.5 per mill (both pyrite and pyrrhotite) [1].
Pb isotope data	Model age, from galena: 2120 or 2070 Ma; from microcline of cross-cutting dyke: 1860 Ma [1], or 1930–1960 Ma [4]. Ore galena: 1918 or 1925 Ma [22].
GEOLOGY
Regional geology map 1		Regional geology map 2
Local geology map 1		Local geology map 2
Geological setting	The deposit is in a 500 m thick, E-W striking, 45° to the S dipping, sequence of 'arenaceous' and calcareous (skarn) rocks located in a mica schist-dominated synform and cut by several faults [1,25,27,28,33]. The full length of the Lampinsaari or Vihanti-type rock sequence is, at least, 60 km [14]. The deposit is in an overturned monocline of a drag-folded volcanic sequence [12,17]. The Zn and Cu lodes are chiefly in the diopside skarns and pyrite lodes in the 'arenaceous rocks' of the sequence [1,17,28]. The 'arenaceous rocks' are in fact volcanic or, at least, of volcanogenic material and located in a formation characterised by turbiditic mica schists, and are 1.90–1.88 Ga in age [17,25,31]. The ore-hosting sequence also contains a bed of phosphoritic tuff(ite) in the same stratigraphic horizon as the pyrite lodes [2,3,4,12,17,28].
Major host rocks	Rhyodacitic porphyry [25].
Minor host rocks	Skarns [25].
Intrusives	Early- (1900 Ma) and synorogenic (1875 Ma) gabbroids and granitoids surround the mica-schist area hosting the ore sequence [1,22,24]. Mafic dykes occur in the sequence as conformable and cross-cutting units [1]. Felsic to intermediate porphyry dykes, parallel to the local faults, cut across the ore and its host rocks and, also, the mafic dykes [1]. There are, in addition, granitic, more coarse-grained dykes which represent the latest intrusives in the area [30].
Outcrop photo 1		Outcrop photo 2
Outcrop photo 3		Outcrop photo 4
METAMORPHISM AND DEFORMATION
Metamorphic history	Peak regional metamorphism at about 1876±2 Ma [2,3,5] related to the intrusion of synorogenic, 1.89–1.87 Ga, granitoids [31].
Metamorphic grade	Transitional between amphibolite and granulite facies [25] or upper-amphibolite facies [1,2], peaked at about 6.8 kbar [21] and 630±10°C [25]. Upper-amphibolite facies (Garnet-cordierite-K feldspar-biotite grade) [31].
Metamorphic mineral assemblages	Mica schist: quartz-biotite-plagioclase ± hornblende, tremolite, cummingtonite, K feldspar, garnet, cordierite, sillimanite, corundum, tourmaline [1]. Black shale: quartz-plagioclase-phlogopite-tremolite-K feldspar-pyrrhotite-pyrite-graphite [1]. Graywacke (= felsic to intermediate volcanic rock) [12,20]: quartz-biotite/phlogopite-plagioclase ± sulphides, hornblende, diopside, tremolite [1]. Cordierite gneiss: quartz-phlogopite-plagioclase ± sulphides, K feldspar, sillimanite [1]. Dolomite: Biotite-dolomite-calcite-diopside-tremolite-olivine-clinohumite-garnet-pyrrhotite [1]. Tremolite skarn: tremolite-quartz-plagioclase-phlogopite-calcite-dolomite-pyrrhote-pyrite ± talc, tourmaline, scapolite, baryte, fluorite, corundum [1]. Diopside skarn: dioside-quartz-plagioclase-phlogopite-calcite-dolomite-pyrrhote-pyrite ± talc, tourmaline, scapolite, baryte, fluorite, corundum [1].
Metamorph photo 1		Metamorph photo 2
Deformation history	At least, four major stages of deformation [13,17] which took place during 1900–1880 Ma [24].
Structure photo 1		Structure photo 2
ALTERATION
Regional alteration	Formation of cordierite and skarn rocks [1]. Skarnified zones common at the contacts between dolomites and greywackes, and skarns and greywackes [1,11].
Local alteration	Cordierite gneiss, derived by alteration form the arenaceous or, rather, felsic volcanic units, is abundant in the W and upper parts and dominates in the hanging wall (there, several tens of metres thick) of the ore-hosting rock sequence [1] (is this the original chlorite±clay mineral zone of alteration??; in any case, it is a Mg-Al-B-enriched rock). Skarns are the most common immediate wallrocks and may, perhaps, show signs of Mg metasomatism in the form of phlogopite or cordierite formation [1]. Also, the dolomites may be Mg-metasomatic derivates of sedimentary/biogenic limestones [25].
Alteration figure 1		Alteration figure 2
Alteration figure 3		Alteration figure 4
Post-mineralisation modifications	Regional metamorphism and polyphase deformation with significant increase in the grain size of the sulphides and, possibly, increase in the thickness of the Zn-lodes by deformation [1,2,12,13,25]. Folding and multi-stage transverse faulting has significantly modified the form of the lodes [1]. Local remobilisation of the sulphides and, especially, sulphosalts into veins [1]. During deformation, the ore and skarn rocks have, in many areas, behaved in a plastic manner whereas the arenaceous interlayer have been much more competent and broken into small fragments within the ore-skarn matrix [1].
TIMING	At about 1.92 Ma [35]. Between about 1960 and 1930 Ma [4]. The sulphides were formed at about 1900 Ma [22,24].
SUPERGENE ALTERATION	In the uppermost parts of the deposit, replacement of pyrrhotite by pyrite, marcasite and limonite and, very locally, formation of chalcosite [1]. Note the conflicting timing information given for the host rocks in 'Geological setting'.
GENETIC MODEL	Submarine felsic-dominated volcanic and subvolcanic activity produced an hydrothermal system which produced, as chemical sediments, the sulphide deposit, carbonate rocks and the U-P rich metasediments [12,20,25,30]. The host formation was originally a single volcanogenic horizon with two main cycles of sulphide precipitation: 1. Fe-sulphides and 2. sphalerite [17]. Early NW- and NE-trending shear and fault zones, located near the margins of the gabbros in the region, may have behaved as conduits for mineralising fluids and even magmas [30]. According to [34], the mineralising fluids may have precipitated the metals below a cap rock formed by low-permeability black shale unit.
GENETIC TYPE	Syngenetic, felsic volcanism- and sediment-related, stratabound [2,12,25].
Schematic model 1		Schematic model 2
References 1. Rouhunkoski, P. 1968. On the geology and geochemistry of the Vihanti zinc ore deposit. Bull. Comm. Geol. Finlande 236. 121 p. 2. Loukola-Ruskeeniemi, K., Kuronen, U. & Arkimaa, H. 1997. Geochemical comparison of metamorphosed black shales associated with the Vihanti zinc deposit and prospects in western Finland. Geol. Surv. Finland, Special Paper 23, 5–13. 3. Rehtijärvi, P. 1984. Distributions of phosphorus, sulphur and sulphur isotopes in a strata-bound base metal deposit, Kangasjärvi, Finland. Geol. Surv. Finland, Report of Investigation 65. 16 p. 4. Rehtijärvi, P., Äikäs, O. & Mäkelä, M. 1979. A middle Precambrian uranium- and apatite-bearing horizon associated with the Vihanti zinc ore deposit, western Finland. Economic Geology 74, 1102–1117. 5. Vaasjoki, M., Äikäs, O. & Rehtijärvi, P. 1980. The age of mid-Proterozoic phosphatic metasediments in Finland as indicated by radiometric U-Pb dates. Lithos 13, 257–262. 6. Laatio, G. 1952. Vihanti. Geol. Surv. Finland, Report Dc N:o 29. 4 p. (in Finnish, 2.2 MB) 7. Kahma, A. 1950. Yhteenveto geologisen tutkimuslaitoksen suorittamista tutkimuksista Lampinsaaren sinkkiesiintymällä Vihannissa. Geol. Surv. Finland, Report M17/Vti-50/3. 9 p. (in Finnish) 8. Vaasjoki, O. 1946. Vihannin näytteiden malmimineraalikokoomus. 3 p. Geol. Surv. Finland, Report M17/Vti-46/3. (in Finnish) 9. Anon. 1958. Selonteko hakemusten alaisten kaivospiirien Lampinsaari 9–16 alueilla suoritetuista tutkimuksista ja niiden tuloksista. Outokumpu Oy, Vihanti mine, Report. (in Finnish) 10. Mikkola, A. 1949. Vihannista lähetetyt kansannäytteet. 2 p. Geol. Surv. Finland, Report M17/Vti-49/2. (in Finnish) 11. Mikkola, A. 1947. Lampinsaaren kiisumalmin kairasydänten tutkiminen. Geol. Surv. Finland, Report M17/Vti-47/1. 7 p. (in Finnish) 12. Rauhamäki, E., Mäkelä, T. & Isomäki, O-P. 1980. Geology of the Vihanti mine. In: Häkli, T.A. (ed.) Precambrian Ores of Finland: Guide to Excursions 078 A+C, Part 2 (Finland). Espoo: Geol. Surv. Finland, 14–24. 13. Lång, K., Gaál, G. & Starostin, V. 1984. Structural and petrophysical features, some Precambrian stratabound base metal deposits of Finland (Outokumpu, Vihanti, Riikonkoski). In: 27th International Geological Congress = 27-j mezdunarodnyh geologiceskij kongress, Moskva, 4–14 avgusta: Tesizy = Abstracts. 6, 186–187. 14. Rauhamäki, E. 1979. Vihannin kaivoksen uraani-fosforimineralisaatio. In: Parkkinen, M. (ed.) Uraaniraaka-ainesymposiumi (1979). Vuorimiesyhdistys. Sarja B 27, 65–79. (in Finnish) 15. Björklund, A., Kontio, M. & Nikkarinen, M. 1976. Vihanti: the geochemical response of bedrock and ore in the overlying till. Journal of Geochemical Exploration 5, 370–373. 16. Pelkonen, K. 1987. Hopeamineraalien esiintymisestä ja rikastettavuudesta Vihannin malmissa. Summary: Silver minerals in the Vihanti ore deposit and their behaviour in concentration process. In: ed. H. Kauppinen, R. Blomqvist, H. Laapas et al. Tuotantomineralogian seminaari 16.1.1986 TKK:n Vuoriteollisuusosastolla. Vuorimiesyhdistys Sarja B 38, 44–56. 17. Kousa, J., Luukas, J., Mäki, T., Ekdahl, E., Pelkonen, K., Papunen, H., Isomäki, O-P., Penttilä, V-J. & Nurmi, P. 1997. Geology and mineral deposits of the central Ostrobothnia. Geol. Surv. Finland, Guide 41, 43–67. 18. Iisalo, E. 1995. Vihannin karttalehden 2434 vanhan moreeniaineiston uudelleen analysointi ICP:llä, tulosten vertailu ja anomaliat. Geol. Surv. Finland, Report S/41/2434/95/1. 16 p. (in Finnish) 19. Kauranne, L-M. 1979. Vihannin karttalehtialueen geokemiallisen kartoituksen tulokset. Summary: The results of the geochemical survey in the Vihanti map-sheet area. Explanation for geochemical maps, Sheet 2434. Geol. Surv. Finland. 55 p. 20. Lestinen, P. 1983. Sulphide deposits of central Finland. Outokumpu, Pyhäsalmi, Vihanti. X IGES – III SMGP Symposium, 1983. Excursion Guide. Espoo: Geol. Surv. Finland. 9 p. 21. Törnroos, R. 1982. Sphalerite geobarometry of some metamorphosed sulphide ore deposits in Finland. Geol. Surv. Finland, Bull. 323. 42 p. 22. Vaasjoki, M. 1981. The lead isotopic compositions of some Finnish galenas. Geol. Surv. Finland, Bull. 316. 30 p. 23. Sotka, P. 1981. Vihanti: Välisaaren ja Isoahon malmimineraalien koostumuksesta. Outokumpu Oy Exploration, Report 070/Vihanti/PMS/1981. 2 p. (in Finnish) 24. Vaasjoki, M. & Sakko, M. 1988. The evolution of the Raahe–Ladoga zone in Finland: isotopic constraints. Geol. Surv. Finland, Bull. 343, 7–32. 25. Papunen, H. (ed.) 1990. Sinkkiprojektin loppuraportti. University of Turku, Institute of Geology and Mineralogy, Publication 22. 143 p. (in Finnish) 26. Tontti, M., Koistinen, E. & Seppänen, H. 1981. Vihannin Zn-Cu-malmivyöhykkeen geomatemaattinen arviointi. Summary: Geomathematical evaluation of the Vihanti Zn-Cu ore zone. Geol. Surv. Finland, Report of Investigation 54. 58 p. 27. Isokangas, P. 1954. The Vihanti zinc deposit. In: Aurola, E. (ed.) The Mines and Quarries of Finland. Geol. Surv. Finland, Geoteknillisiä julkaisuja 55, 29–32. 28. Autere, I., Pelkonen, K. & Pulkkinen, K. 1991. Outokumpu Finnmines Oy:n Vihannin kaivos. Summary: Outokumpu Finnmines Oy's Vihanti zinc mine. Vuoriteollisuus 49, 81–88. 29. Wennervirta, H. 1968. Litogeokemiallinen tutkimus, Vihannin malmikompleksi. Outokumpu Oy Exploration, Report 061/2434 05/604/HW/68. (in Finnish) 30. Kuronen, U. 1988. Ajatuksia vuosina 1984–1987 Vihannin alueella suoritetuista tutkimuksista. Outokumpu Oy Exploration, Report 020/2434/UOK/88. (in Finnish) 31. Korsman, K. (ed.) & Glebovitsky, V. (ed.) 1999. Raahe–Ladoga Zone structure-lithology, metamorphism and metallogeny: a Finnish–Russian cooperation project 1996–1999. Map 2: Metamorphism of the Raahe–Ladoga Zone 1:1000000. Geol. Surv. Finland. 32. Salli, I. 1958. Vihanti. Geological Map of Finland 1:100000. Pre-Quaternary Rocks, Sheet 2434. Geol. Surv. Finland. 33. Salli, I. 1965. Pre-Quaternary Rocks of the Pyhäjoki and Vihanti Map-Sheet areas. Geological Map of Finland 1:100000. Explanation to the Maps of Pre-Quaternary Rocks, Sheets 2432–2 434. Geol. Surv. Finland. 52 p. 34. Loukola-Ruskeeniemi, K. 1999. Origin of black shales and the serpentinite-associated Cu-Zn-Co ores at Outokumpu, Finland. Econ. Geol. 94, 1007–1028. 35. Lahtinen, R., Korja, A. & Nironen, M. 2001. Evolution and metallogeny if the Paleoproterozoic Svecofennian Orogen. In: Williams P.J. (ed.) 2001: A Hydrothermal Odyssey. May 17–1 9th, 2001, Townsville. Extended abstracts. EGRU and JCU. 110–111.
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